1. Field of the Invention
The present invention relates to a microcontroller for a control device for an internal combustion engine, to a control device for an internal combustion engine, to a method for the functional controlling of a microcontroller, and to a computer program for the functional limiting of a microcontroller.
2. Description of the Related Art
The task of an engine control device of an internal combustion engine is to calculate output quantities for actuating elements (such as injection nozzles or an ignition system) from a multiplicity of input signals (such as rotational speed, temperature, or pressure). For this purpose, a control device has a microcontroller having its own storage device (so-called on-chip storage), in which the data, characteristic maps, and/or programs required for the calculation—also generally referred to below as internal data—are stored.
During the manufacturing of the control device, particular storage regions are written to by the manufacturer of the control device, standardly a supplier company, with programs (firmware), data, and/or characteristic maps. The control device written to in this way is supplied to the vehicle manufacturer, who may make further changes to the data and characteristic maps in order to optimally calibrate the control device to the internal combustion engine. The data, characteristic maps, and/or programs are specified, on the basis of intensive research and testing, in such a way that the internal combustion engine operates so as to protect components and the environment to the greatest possible extent. In particular, the internal data are specified in such a way that even in extreme conditions no damage to the internal combustion engine will occur. Through corresponding reprogramming (so-called chip tuning) of the microcontroller in the control device, therefore, more or less large increases in efficiency are possible.
A manipulation of internal data of the microcontroller can thus result in changed vehicle behavior.
For the purposes of development and analysis, it is necessary that access remain possible to such internal data. For example, the access permits an error analysis in the case of device failure, and takes place via an analysis access of the microcontroller.
If, however, via the analysis access internal data of the microcontroller are read out and changed by an unauthorized person, vehicle manufacturers or suppliers can no longer predict the behavior of the vehicle. Correspondingly, a customer cannot be given product guarantees if the data have been manipulated.
It is desirable to prevent unauthorized access to a microcontroller, and thus to increase operational reliability.